Both have already: Barca sold Cesc Fabregas to Chelsea and Alexis Sanchez to Arsenal, while Madrid striker Alvaro Morata has joined Juventus and the Spanish side also sent Casemiro on loan to Porto.

But with the window still open and more arrivals likely at both clubs, Spain's two biggest teams will be looking to trim their squads and recoup funds in the coming weeks.

Here, Goal takes a look at the players who could still leave Camp Nou and the Santiago Bernabeu this summer.

IKER CASILLAS / DIEGO LOPEZ

Iker Casillas and Diego Lopez shared the responsibilities between the sticks at Real Madrid last season, with the captain starting in the Copa del Rey and the Champions League and the former Villarreal man favoured in La Liga.

However, Madrid are close to sealing the signing of Levante shot-stopper Keylor Navas, meaning one of the two will almost certainly leave the Santiago Bernabeu this summer.

Casillas is wanted by Arsenal, but is set to wait to see whether he starts the Uefa Super Cup on August 12 before making a decision on his future. If he does decide to leave, he would hope to persuade the club to release him on a free transfer.

Lopez, meanwhile, is a target for Monaco (who tried to sign him last summer) and will consider a move if he is told he is not first choice by coach Carlo Ancelotti. He would cost in the region of £8m.

ANGEL DI MARIA (

Just like last summer, Angel Di Maria has looked certain to leave, but the Argentine could yet stay on at Real Madrid.

The 26-year-old winger (valued at £47m by Madrid) is a popular player at the Bernabeu and was crucial as the club claimed both the Copa del Rey and the Champions League last term.

The signings of Kroos and James mean competition for places will be even more intense this time around, yet Madrid may decide to keep him as they aim to win six titles in 2014-15.

Paris Saint-Germain remain interested, with Manchester United also monitoring his situation. Madrid, though, are in no hurry to do a deal and will only sell if they bring in a striker before the end of the transfer window or if their valuation is met and the player himself wants to leave.

ISCO

Isco initially rejected a move to Real Madrid last summer because he thought he would struggle to hold down a first-team place - and so it proved.

The former Malaga man spent much of the season on the bench, but did make over 50 appearances in the end and is popular with both team-mates and fans.

At 22, he is keen to stay and prove he can be a hit at the Bernabeu, but faces intense competition for places in what would be his second season at the club.

His former boss Manuel Pellegrini is eager to take him to Manchester City and Isco was set on a move to the Etihad before Madrid's intervention last year. If he believes his opportunities are limited this time around, he could choose to join the Premier League champions. Bayern Munich are also interested, but the player would favour a link-up with Pellegrini. He would cost around £27m.

SAMI KHEDIRA (

Sami Khedira spent most of last season recovering from an injury to his anterior cruciate ligament and only just made it back in time for the World Cup with Germany.

With Toni Kroos signed, Xabi Alonso still at the Bernabeu, Luka Modric impressive last season and Asier Illarramendi set to stay, Khedira knows he could find himself on the bench next term and is stalling on a new contract.

The German's current deal expires in 2015 and, if he refuses to sign a new one, Madrid will look to sell him for the same price they bought Kroos: £23m.

Arsenal and Chelsea are both interested, but both are keen to knock down the asking price and the midfielder's huge wage demands.

IBRAHIM AFELLAY

Ibrahim Afellay's Barcelona career has been plagued by injury and the Dutch winger is finally set to move on this summer.

Signed for a cut-price £2.3m deal from PSV in January of 2011, the midfielder has made just 35 appearances for the Catalan club and spent a season on loan at Schalke in 2012-13.

Sporting director Andoni Zubizarreta admitted on Thursday that the 28-year-old may move on this summer, with Barca keen to recoup some funds for the player before his contract expires next year.

Feyenoord are keen on a move, but believe the midfielder will be out of their price range - even though he'll be allowed to leave on the cheap. Marseille and Valencia have also made enquiries.

DANI ALVES

Dani Alves had made his mind up to leave Barcelona before the World Cup, but has since changed his mind and recently said he would like to extend his stay at Camp Nou.

Barcelona, however, have other ideas. The Catalan club grew impatient with the Brazilian's poor attitude in training and lack of focus last season, so the 31-year-old will have to prove himself all over again this summer if he is to work under Luis Enrique next term.

Barca remain interested in Colombia winger Juan Cuadrado, while they are also pleased with the progress of youngster Martin Montoya at right-back. Cuadrado is more of an attacking player than Alves, but Barca could switch to a three-man defence next term, with Javier Mascherano used in midfield and dropping deep to cover and Cuadrado in a wing-back role. The Colombian's arrival could very well hold the key to Alves' future.

Paris Saint-Germain look to have ended their interest by signing right-back Serge Aurier on loan from Toulouse, but Monaco could make a move for Alves. However, the player's high wage demands (around £6m per year) may mean he ends up staying at Barca, who want at least £9.5m for the Brazilian.

ALEX SONG

Almost certain to leave Barcelona this summer is Alex Song, who has failed to impress in his two seasons at the Catalan club.

Sporting director Zubizarreta revealed on Thursday that the Blaugrana were trying to find a solution for both Afellay and Song, with the Cameroonian having made 65 appearances in two years - mostly from the bench.

Song has himself said he would favour a return to the Premier League, where he played for several seasons with Arsenal.

However, the player has attracted more interest from France and Italy, with Milan and Napoli both weighing up a move for the 26-year-old, possibly on loan with a view to a permanent transfer in future. He is valued at £12m by Barca, but the club are likely to accept around £9.5m.